1. Introduction

The Gateway is the entry point into a UNICORE site, routing HTTPS
traffic to servers like UNICORE/X. It is installed in front of any
networking firewall. It authenticates incoming messages and forwards
them to their intended destination. The Gateway receives the reply and
sends it back to the client. In this way, only a single open port in a
site’s firewall has to be configured.

Note

LIMITATIONS

This forwarding process only works for “most” HTTP requests, and is
not a complete HTTP reverse proxy implementation. For example, it is
not possible to run a full, complex web application like the UNICORE
portal "behind" the gateway. Check the respective components’s manual
whether it can be run behind the Gateway.

In effect, traffic to a virtual URL, e.g.
https://mygateway:8088/Alpha is forwarded to the real URL, e.g.
https://host1:7777.

The mappings of virtual URL to real URL for the available sites are
listed in a configuration file connections.properties.
Additionally, the gateway supports dynamic registration of sites.

The second functionality of the gateway is authentication of incoming
requests. Connections to the gateway are made using
client-authenticated SSL, so the gateway will check whether the caller
presents a certificate issued by a trusted authority. Information about
the authenticated client is forwarded to services behind the gateway in
UNICORE proprietary format (as SOAP header element).

Note

IMPORTANT NOTE ON PATHS

The UNICORE Gateway is distributed either as a platform independent and
portable bundle (as a part of the UNICORE core server package) or as an
installable, platform dependent package format such as RPM.

Depending on the installation method, the paths to various Gateway files
are different. If installing using a distribution-specific package the
following paths are used:

CONF=/etc/unicore/gateway
BIN=/usr/sbin
LOG=/var/log/unicore/gateway

If installing using the portable bundle all Gateway files are installed
under a single directory. Path prefixes then are as follows, where INST
is a directory where the Gateway was installed:

CONF=INST/conf
BIN=INST/bin
LOG=INST/log

The above variables (CONF, BIN and LOG) are used throughout the rest of
this manual.

2. Installation

The UNICORE Gateway is distributed in the following formats:

As a part of platform independent installation bundle called UNICORE core server bundle.
The UNICORE core server bundle is provided in two forms: one with a graphical installer and
one with a command line installer.

As a binary, platform-specific package available currently for
RedHat (Centos) and Debian platforms. Those packages are not tested
on all possible platforms, but should work without any problems with
other versions of similar distributions, e.g. SL6, Centos, or Fedora.

2.1. Installation from the core server bundle

Download the core server bundle from the UNICORE project website.

If you use the graphical installer, follow the on-screen instructions and do not forget
to enable the Gateway checkbox when prompted.

If you use the console installer, please review the README file available after
extracting the bundle. You don’t have to change any defaults as the Gateway is installed
by default.

2.2. Installation from a Linux package (rpm or deb)

Use your distribution’s package manager to install.

3. Upgrading

The general update procedure is presented below, with possible variations:

Stop the old Gateway.

Update the server package. This step mostly applies for RPM/DEB managed installations. For Quickstart installation
it is enough to replace the *.jar files with the new ones.

Start the newly installed Gateway.

Verify log file and fix any problems reported.

4. Configuration

The gateway is configured using a set of configuration files, which
reside in the CONF subdirectory.

4.1. Java and environment settings: startup.properties

This file contains settings related to the Java VM, such as the Java command
to use, memory settings, library paths etc.

4.2. Configuring sites: connections.properties

This is a simple list connecting the names of sites and their physical addresses.
An example is:

DEMO-SITE = https://localhost:7777
REGISTRY = https://localhost:7778

If this file is modified, the gateway will re-read it at runtime, so there is no need to
restart the gateway in order to add or remove sites.

Optionally administrator can enable a possibility for dynamic site registration at runtime,
see [dyn-reg] for details. Then this file should contain only the static entries (or
none if all sites register dynamically).

Further options for back-end sites configuration are presented in [loadbalance].

4.3. Main server settings: gateway.properties

Use the gateway.hostname property to configure the network interface and
port the gateway will listen on. You can also select between https and http protocol,
though in almost all cases https will be used.

Example:

gateway.hostname = https://192.168.100.123:8080

Note

If you set the host to 0.0.0.0, the gateway will listen on all network interfaces
of the host machine, else it will listen only on the specified one.

If the scheme of the hostname URL is set to https, the Gateway uses the configuration
data from security.properties to configure the HTTPS settings.

4.4. Certificate-less end-user access

With UNICORE 7, it is possible that end-users do not have client
certificates. To enable them to connect, the Gateway needs to accept
TLS connections without a client certificate. To configure this, set
the following in gateway.properties

gateway.httpServer.requireClientAuthn=false

4.4.1. Scalability settings

To fine-tune the operational parameters of the embedded Jetty server, you can set advanced HTTP server
parameters. See [ref-jetty] for details.
Among others you can use the non-blocking IO connector offered by Jetty,
which will scale up to higher numbers of concurrent connections than the default connector.

The gateway acts as a https client for the VSites behind it.
The number of concurrent calls is limited, and controlled by two parameters:

# maximum total number of concurrent calls to Vsites
gateway.client.maxTotal=100
# total number of concurrent calls per site
gateway.client.maxPerService=20

You can also control the limit on the maximum SOAP header size which is allowed by the
gateway. Typically you don’t have to touch this parameter. However if your clients
do produce very big SOAP headers and gateway blocks them, you can increase the limit. Note
that such a giant SOAP header usually means that the client is not behaving in a sane way,
e.g. is trying to perform a DoS attack.

Note that gateway may consume this amount of memory (plus some extra amount
for other data) for each opened connection. Therefore, this value multiplied by
the number of maximum allowed connections, should be significantly lower, then the total
memory available for the gateway.

4.4.2. Dynamic registration of Vsites

Dynamic registration is controlled by three properties in CONF/gateway.properties file:

gateway.registration.enable=true

If set to true, the gateway will accept dynamic registrations which are made by
sending a HTTP POST request to the URL /VSITE_REGISTRATION_REQUEST

Filters can be set to forbid access of certain hosts, or to require certain strings
in the Vsite addresses. For example:

gateway.registration.deny=foo.org example.org

will deny registration if the remote hostname contains foo.org or example.org.
Conversely,

gateway.registration.allow=mydomain.org

will only accept registrations if the remote address contains mydomain.org.
These two (deny and allow) can be combined.

4.4.3. Web interface ("monkey page")

For testing and simple monitoring purposes, the gateway displays a website
showing detailed site information (the details view can be disabled).
Once the Gateway is running, open up a browser and navigate to
https://<gateway_host>:8080 (or whichever URL the gateway is running on).
As the gateway usually runs using SSL, you will need to import a suitable
client certificate into your web browser.

A HTML form for testing the dynamic registration is available as well,
by clicking the link in the footer of the main gateway page.

To disable the Vsite details page, set

gateway.disableWebpage=true

4.4.4. Main options reference

Property name

Type

Default value / mandatory

Description

gateway.hostname

string

mandatory to be set

external gateway bind address

gateway.registration.allow

string

-

Space separated list of allowed hosts for dynamic registration.

gateway.registration.deny

string

-

Space separated list of denied hosts for dynamic registration.

gateway.registration.enable

[true, false]

false

Whether dynamic registration of sites is enabled.

--- Passing Consignor info ---

gateway.consignorTokenTimeTolerance

integer >= 0

30

The validity time of the authenticated client information passed to backend sites will start that many seconds before the real authentication. It is used to mask time synchronization problems between machines.

gateway.consignorTokenValidity

integer >= 1

60

What is the validity time of the authenticated client information passed to backend sites. Increase it if there machines clocks are not synhronized.

gateway.signConsignorToken

[true, false]

false

Controls whether information about the authenticated client (the consignor) passed to backend sites should be signed, or not. Signing is slower, but is required when sites may be reached directly, bypassing the Gateway.

Controls whether the HTTP expec-continue mechanism is enaled on connections to backend sites.

gateway.client.gzip

[true, false]

true

Controls whether support for compression is announced to backend sites.

gateway.client.keepAlive

[true, false]

true

Whether to keep alive the connections to backend sites.

gateway.client.maxPerService

integer number

20

Maximum allowed number of connections per backend site.

gateway.client.maxTotal

integer number

100

Maximum total number of connections to backend sites allowed.

gateway.client.socketTimeout

integer number

30000

Connection timeout, used when connecting to backend sites.

--- Advanced ---

gateway.disableWebpage

[true, false]

false

Whether the (so called monkey) status web page should be disabled.

gateway.externalHostname

string

not set

External address of the gateway, when it is accessible through a frontend server as Apache HTTP.

gateway.soapMaxHeader

integer [1024 — 1024000000]

102400

Size in bytes of the accepted SOAP header. In the most cases you don’t need to change it.

4.5. security.properties

In the security.properties file, the trust store and gateway credential is configured.

4.5.1. Proxy certificate support

The UNICORE gateway optionally accepts proxy certificates as used by other Grid middleware systems.
In general, we think proxies are a bad idea, but for interoperability purposes, proxies
support can be enabled. If enabled, the clients using proxies are authenticated as the
initial issuer of the presented proxy certificates chain. See the above reference properties
table for the actual setting.

The most important, root log categories used by the Gateway’s logging are:

unicore.gateway

General gateway logging

unicore.connections

Log IPs of clients, and the DN after the SSL handshake

unicore.httpserver

HTTP processing, Jetty server

unicore.security

Certificate details and other security

The Gateway uses the so called MDC (Mapped Diagnostic Context) to provide
additional information on the client which is served. In the MDC the client’s IP address and
client’s Distinguished Name is stored. You can control whether to attach MDC to each
line by the %X{entry} log4j pattern entry. As the entry you can use: clientIP or clientName.
For example:

6. Using the Gateway for failover and/or loadbalancing of UNICORE sites

The Gateway can be used as a simple failover solution and/or loadbalancer to achieve
high availability and/or higher scalability of UNICORE/X sites without additional tools.

A site definition (in CONF/connections.properties) can be extended, so that multiple physical
servers are used for a single virtual site.

An example for such a so-called multi-site declaration in the connections.properties file
looks as follows:

#declare a multisite with two physical servers
MYSITE=multisite:vsites=https://localhost:7788 https://localhost:7789

This will tell the gateway that the virtual site "MYSITE" is indeed a multi-site with the
two given physical sites.

6.1. Configuration

Configuration options for the multi-site can be passed in two ways. On the one hand they can
go into the connections.properties file, by putting them in the multi-site definition, separated
by ";" characters:

#declare a multisite with parameters
MYSITE=multisite:param1=value1;param2=value2;param3=value3;...

The following general parameters exist

vsites

List of physical sites

strategy

Class name of the site selection strategy to use (see below)

config

Name of a file containing additional parameters

Using the "config" option, all the parameters can be placed in a separate file for enhanced
readability. For example you could define in connections.properties:

#declare a multisite with parameters read from a separate file
MYSITE=multisite:config=conf/mysite-cluster.properties

6.2. Available Strategies

A selection strategy is used to decide where a client request will
be routed. By default, the strategy is "Primary with fallback", i.e. the request
will go to the first site if it is available, otherwise it will go to the second site.

Primary with fallback

This strategy is suitable for a high-availability scenario, where a secondary site takes over
the work in case the primary one goes down for maintenance or due to a problem. This is the
default strategy, so nothing needs to be configured to enable it. If you want to explicitely
enable it anyway, set

strategy=primaryWithFallback

The strategy will select from the first two defined physical sites. The first, primary one will
be used if it is available, else the second one. Health check is done on each request, but not
more frequently as specified by the "strategy.healthcheck.interval" parameter. By default, this parameter
is set to 5000 milliseconds.

Changes to the site health will be logged at "INFO" level, so you can see when the sites go up or down.

Round robin

This strategy is suitable for a load-balancing scenario, where a random site will be chosen from
the available ones. To enable it, set

strategy=roundRobin

Changes to the site health will be logged at "INFO" level, so you can see when the sites go up or down.

It is very important to be aware that this strategy requires that all backend sites used in the pool,
share a common persistence. It is because Gateway does not track clients, so particular client requests
may land at different sites. This is typically solved by using a non-default, shared database for sites,
such as MySQL.

Note

Currently loadbalancing of target sites is an experimental feature and is not yet fully functional.
It will be improved in future UNICORE versions.

Custom strategy

You can implement and use your own failover strategy, in this case, use the name of the Java class as
strategy name:

strategy=your_class_name

7. Gateway failover and migration

The [loadbalance] covered usage of the Gateway to provide failover of backend services.
However it may be needed to guarantee high-availabilty for the Gateway itself or to move it
to other machine in case of the original one’s failure.

7.1. Gateway’s migration

The Gateway does not store any state information, therefore its migration is easy.
It is enough to install the Gateway at the target machine (or even to simply copy
it in the case of installation from the core server bundle) and to make sure that
the original Gateway’s configuration is preserved.

If the new machine uses a different address, it needs to be reflected in the
server’s configuration file (the listen address). Also, the
configuration of sites behind the gateway must be updated accordingly.

7.2. Failover and loadbalancing of the Gateway

Gateway itself doesn’t provide any features related to its own redundancy. However as it
is stateless, the standard redundancy solutions can be used.

The simpliest solution is to use Round Robin DNS, where DNS server routes the Gateway’s DNS
address to a pool of real IP addresses. While easy to set up this solution has a
significant drawback: DNS server doesn’t care about machines being down.

The much better choice is to use the Linux-HA software suite, often known under the name of
its principal component, the heartbeat. For details see http://www.linux-ha.org

Additionally a more advanced HTTP-aware software can be used, such as HA-Proxy (http://haproxy.1wt.eu).
Currently Gateway and UNICORE don’t maintain HTTP sessions so usage of the HTTP-aware
load-balancer is not strictly required, but such solutions generally provide more
general purpose features.